The present invention relates to a method for assisting an operator of a vehicle in the vehicle stabilization, wherein an additional steering torque is applied to the steering line of the vehicle.
Further, the invention relates to a device for assisting an operator of a vehicle, comprising a means for applying an additional steering torque to a steering line of a vehicle.
A large number of modern vehicles are already equipped with yaw rate control (ESP) which stabilizes a vehicle in critical driving situations. This control is based on wheel-individual brake interventions and interventions into engine control being performed when the vehicle behavior differs from a predetermined desired behavior. The control interventions are distinctly noticeable to the operator of the vehicle and, hence, very uncomfortable so that they are usually carried out only after a major deviation from the desired behavior has been identified.
It is also known in the art to set a steering angle stabilizing the driving condition of the vehicle in critical driving situations by way of control interventions into the steering system of the vehicle irrespective of the steering instructions of the operator. These interventions are not felt by the driver as a major impairment and can thus be performed already when insignificant deviations from the desired behavior occur. However, to this end, the vehicle must be equipped with an appropriate steering system, for example, an overriding steering system or a steer-by-wire steering system. Also, there is the risk of faulty control interventions which may considerably jeopardize the stability of the vehicle.
In view of the above, it is desirable to merely assist the driver of the vehicle at the start of an unstable driving behavior and, in particular, in his course holding task, without directly adjusting correcting variables such as the steering angle of the vehicle.
International patent application WO 02/062647 A1 describes a steering system for a vehicle where the operator of a vehicle receives haptic information about the driving condition. Depending on a difference between the yaw rate of the vehicle and a reference yaw rate, an electric motor is used to adjust a steering torque which renders the steering system easily movable or more difficult to move.
However, this arrangement does not provide the driver with specific instructions how to stabilize the vehicle in the presence of an unstable driving condition. In particular inexperienced drivers do not know, e.g. in an understeering or oversteering situation, however, in which way they have to react in order to reach a stable driving condition.
In view of the above, an object of the invention involves improving a method of the type mentioned hereinabove to such extent that the driver of a vehicle is reliably assisted in stabilizing the vehicle.